The strength of sex-specific selection in the wild.

Anisogamy predisposes the sexes to very different patterns of selection on shared traits. Selective differences between the sexes may manifest as changes in the direction or strength of selection acting on shared phenotypes. Although previous studies have found evidence for widespread differences in the direction of selection between the sexes, surprisingly little is known regarding potential differences in the magnitude of selection and whether such differences might be confined to specific components of fitness. We conducted a meta-analysis using 865 estimates of phenotypic selection from wild populations to characterize sex differences in the strength of selection and to ask whether different components of fitness exhibit differences in sex bias in the strength of selection. Overall, consistent with past results, we find evidence of male bias in the strength of selection, driven primarily by components of fitness related to mating success and we discuss several evolutionary implications.